Printhead integrated circuit with an ink ejecting surface.

ABSTRACT

Provided is a printhead integrated circuit defining an external surface having a number of ink ejection ports operatively directed at a printing medium. The surface includes a plurality of petal formations radially positioned about each ink ejection port, and a plurality of actuators, each located behind a petal formation distal from said port. The surface also includes a plurality of heater structures each connected to an actuator, so that heating of the structures via an electrical current produces expansion in said actuators which urges the formations into a chamber below the surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.11/442,160 filed May 30, 2006, which is a continuation of U.S.application Ser. No. 11/055,203 filed Feb. 11, 2005, now issued as U.S.Pat. No. 7,086,721, which is a continuation of U.S. application Ser. No.10/808,582 filed Mar. 25, 2004, now issued as U.S. Pat. No. 6,886,918,which is a continuation of U.S. application Ser. No. 09/854,714 filedMay 14, 2001, now issued as U.S. Pat. No. 6,712,986, which is acontinuation of U.S. application Ser. No. 09/112,806, filed Jul. 10,1998, issued as U.S. Pat. No. 6,247,790. The [the] entire contents ofU.S. application Ser. Nos. 10/808,582 and 09/854,714 are hereinincorporated by reference.

CROSS REFERENCES TO RELATED APPLICATIONS

The following Australian provisional patent applications are herebyincorporated by cross-reference. For the purposes of location andidentification, US patent applications identified by their US patentapplication serial numbers (USSN) are listed alongside the Australianapplications from which the US patent applications claim the right ofpriority. US PATENT/ CROSS-REFERENCED PATENT APPLICATION AUSTRALIAN(Claiming Right of Priority from Provisional Patent AustralianProvisional Application No. Application) Docket No. PO7991 6750901ART01US PO8505 6476863 ART02US PO7988 6788336 ART03US PO9395 6322181ART04US PO8017 6597817 ART06US PO8014 6227648 ART07US PO8025 6727948ART08US PO8032 6690419 ART09US PO7999 6727951 ART10US PO8030 6196541ART13US PO7997 6195150 ART15US PO7979 6362868 ART16US PO7978 6831681ART18US PO7982 6431669 ART19US PO7989 6362869 ART20US PO8019 6472052ART21US PO7980 6356715 ART22US PO8018 6894694 ART24US PO7938 6636216ART25US PO8016 6366693 ART26US PO8024 6329990 ART27US PO7939 6459495ART29US PO8501 6137500 ART30US PO8500 6690416 ART31US PO7987 7050143ART32US PO8022 6398328 ART33US PO8497 7110024 ART34US PO8020 6431704ART38US PO8504 6879341 ART42US PO8000 6415054 ART43US PO7934 6665454ART45US PO7990 6542645 ART46US PO8499 6486886 ART47US PO8502 6381361ART48US PO7981 6317192 ART50US PO7986 6850274 ART51US PO7983 09/113054ART52US PO8026 6646757 ART53US PO8028 6624848 ART56US PO9394 6357135ART57US PO9397 6271931 ART59US PO9398 6353772 ART60US PO9399 6106147ART61US PO9400 6665008 ART62US PO9401 6304291 ART63US PO9403 6305770ART65US PO9405 6289262 ART66US PP0959 6315200 ART68US PP1397 6217165ART69US PP2370 6786420 DOT01US PO8003 6350023 Fluid01US PO8005 6318849Fluid02US PO8066 6227652 IJ01US PO8072 6213588 IJ02US PO8040 6213589IJ03US PO8071 6231163 IJ04US PO8047 6247795 IJ05US PO8035 6394581 IJ06USPO8044 6244691 IJ07US PO8063 6257704 IJ08US PO8057 6416168 IJ09US PO80566220694 IJ10US PO8069 6257705 IJ11US PO8049 6247794 IJ12US PO80366234610 IJ13US PO8048 6247793 IJ14US PO8070 6264306 IJ15US PO80676241342 IJ16US PO8001 6247792 IJ17US PO8038 6264307 IJ18US PO80336254220 IJ19US PO8002 6234611 IJ20US PO8068 6302528 IJ21US PO80626283582 IJ22US PO8034 6239821 IJ23US PO8039 6338547 IJ24US PO80416247796 IJ25US PO8004 6557977 IJ26US PO8037 6390603 IJ27US PO80436362843 IJ28US PO8042 6293653 IJ29US PO8064 6312107 IJ30US PO93896227653 IJ31US PO9391 6234609 IJ32US PP0888 6238040 IJ33US PP08916188415 IJ34US PP0890 6227654 IJ35US PP0873 6209989 IJ36US PP09936247791 IJ37US PP0890 6336710 IJ38US PP1398 6217153 IJ39US PP25926416167 IJ40US PP2593 6243113 IJ41US PP3991 6283581 IJ42US PP39876247790 IJ43US PP3985 6260953 IJ44US PP3983 6267469 IJ45US PO79356224780 IJM01US PO7936 6235212 IJM02US PO7937 6280643 IJM03US PO80616284147 IJM04US PO8054 6214244 IJM05US PO8065 6071750 IJM06US PO80556267905 IJM07US PO8053 6251298 IJM08US PO8078 6258285 IJM09US PO79336225138 IJM10US PO7950 6241904 IJM11US PO7949 6299786 IJM12US PO80606866789 IJM13US PO8059 6231773 IJM14US PO8073 6190931 IJM15US PO80766248249 IJM16US PO8075 6290862 IJM17US PO8079 6241906 IJM18US PO80506565762 IJM19US PO8052 6241905 IJM20US PO7948 6451216 IJM21US PO79516231772 IJM22US PO8074 6274056 IJM23US PO7941 6290861 IJM24US PO80776248248 IJM25US PO8058 6306671 IJM26US PO8051 6331258 IJM27US PO80456110754 IJM28US PO7952 6294101 IJM29US PO8046 6416679 IJM30US PO93906264849 IJM31US PO9392 6254793 IJM32US PP0889 6235211 IJM35US PP08876491833 IJM36US PP0882 6264850 IJM37US PP0874 6258284 IJM38US PP13966312615 IJM39US PP3989 6228668 IJM40US PP2591 6180427 IJM41US PP39906171875 IJM42US PP3986 6267904 IJM43US PP3984 6245247 IJM44US PP39826315914 IJM45US PP0895 6231148 IR01US PP0869 6293658 IR04US PP08876614560 IR05US PP0885 6238033 IR06US PP0884 6312070 IR10US PP08866238111 IR12US PP0877 6378970 IR16US PP0878 6196739 IR17US PP08836270182 IR19US PP0880 6152619 IR20US PO8006 6087638 MEMS02US PO80076340222 MEMS03US PO8010 6041600 MEMS05US PO8011 6299300 MEMS06US PO79476067797 MEMS07US PO7944 6286935 MEMS09US PO7946 6044646 MEMS10US PP08946382769 MEMS13US

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to the field of inkjet printing and, inparticular, discloses an inverted radial back-curling thermoelastic inkjet printing mechanism.

BACKGROUND OF THE INVENTION

Many different types of printing mechanisms have been invented, a largenumber of which are presently in use. The known forms of printers have avariety of methods for marking the print media with a relevant markingmedia. Commonly used forms of printing include offset printing, laserprinting and copying devices, dot matrix type impact printers, thermalpaper printers, film recorders, thermal wax printers, dye sublimationprinters and ink jet printers both of the drop on demand and continuousflow type. Each type of printer has its own advantages and problems whenconsidering cost, speed, quality, reliability, simplicity ofconstruction and operation etc.

In recent years the field of ink jet printing, wherein each individualpixel of ink is derived from one or more ink nozzles, has becomeincreasingly popular primarily due to its inexpensive and versatilenature.

Many different techniques of ink jet printing have been invented. For asurvey of the field, reference is made to an article by J Moore,“Non-Impact Printing: Introduction and Historical Perspective”, OutputHard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).

Ink Jet printers themselves come in many different forms. Theutilization of a continuous stream of ink in ink jet printing appears todate back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hanselldiscloses a simple form of continuous stream electro-static ink jetprinting.

U.S. Pat. No. 3,596,275 by Sweet also discloses a process of acontinuous ink jet printing including a step wherein the ink jet streamis modulated by a high frequency electro-static field so as to causedrop separation. This technique is still utilized by severalmanufacturers including Elmjet and Scitex (see also U.S. Pat. No.3,373,437 by Sweet et al).

Piezoelectric ink jet printers are also one form of commonly utilizedink jet printing device. Piezoelectric systems are disclosed by Kyseret. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragmmode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) whichdiscloses a squeeze mode form of operation of a piezoelectric crystal,Stemme in U.S. Pat. No. 3,747,120 (1972) which discloses a bend mode ofpiezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 whichdiscloses a piezoelectric push mode actuation of the ink jet stream andFischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode typeof piezoelectric transducer element.

Recently, thermal ink jet printing has become an extremely popular formof ink jet printing. The ink jet printing techniques include thosedisclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S.Pat. No. 4,490,728. Both the aforementioned references disclose ink jetprinting techniques which rely on the activation of an electrothermalactuator which results in the creation of a bubble in a constrictedspace, such as a nozzle, which thereby causes the ejection of ink froman aperture connected to the confined space onto a relevant print media.Printing devices utilizing the electro-thermal actuator are manufacturedby manufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printingtechnologies are available. Ideally, a printing technology should have anumber of desirable attributes. These include inexpensive constructionand operation, high speed operation, safe and continuous long termoperation etc. Each technology may have its own advantages anddisadvantages in the areas of cost, speed, quality, reliability, powerusage, simplicity of construction and operation, durability andconsumables.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there isprovided an inkjet printhead for printing on a media substrate, theprinthead comprising:

a wafer substrate defining a plurality of nozzle chambers for storingink to be ejected, each of the nozzle chambers having an outer wall thatfaces the media substrate during use, the wall having an ink ejectionport and at least one actuator for moving the ink ejection port awayfrom the media substrate to eject ink from the corresponding nozzlechamber via the ink ejection port.

By incorporating one or more actuators into the outer wall so that theejection port can be depressed into the nozzle chamber, there are noejection actuators in the interior of the chamber to impede ink refill.Furthermore, as the outer wall returns to its quiescent configurationafter ejection, it draws ink into the chamber as well as the surfacetension of the meniscus at the port.

Preferably there is a plurality of actuators in the wall.

The actuators can include a surface which bends inwards away from thecentre of the nozzle chamber upon actuation. The actuators arepreferably actuated by means of a thermal actuator device. The thermalactuator device may comprise a conductive resistive heating elementencased within a material having a high coefficient of thermalexpansion. The element can be serpentine to allow for substantiallyunhindered expansion of the material. The actuators are preferablyarranged radially around the nozzle rim.

The actuators can form a membrane between the nozzle chamber and anexternal atmosphere of the arrangement and the actuators bend away fromthe external atmosphere to cause an increase in pressure within thenozzle chamber thereby initiating a consequential ejection of ink fromthe nozzle chamber. The actuators can bend away from a central axis ofthe nozzle chamber.

The nozzle arrangement can be formed on the wafer substrate utilizingmicro-electro mechanical techniques and further can comprise an inksupply channel in communication with the nozzle chamber. The ink supplychannel may be etched through the wafer. The nozzle arrangement mayinclude a series of struts which support the nozzle rim.

The arrangement can be formed adjacent to neighbouring arrangements soas to form a pagewidth printhead.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

FIGS. 1-3 are schematic sectional views illustrating the operationalprinciples of the preferred embodiment;

FIG. 4(a) and FIG. 4(b) are again schematic sections illustrating theoperational principles of the thermal actuator device;

FIG. 5 is a side perspective view, partly in section, of a single nozzlearrangement constructed in accordance with the preferred embodiments;

FIGS. 6-13 are side perspective views, partly in section, illustratingthe manufacturing steps of the preferred embodiments;

FIG. 14 illustrates an array of ink jet nozzles formed in accordancewith the manufacturing procedures of the preferred embodiment;

FIG. 15 provides a legend of the materials indicated in FIGS. 16 to 23;and

FIG. 16 to FIG. 23 illustrate sectional views of the manufacturing stepsin one form of construction of a nozzle arrangement in accordance withthe invention.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the preferred embodiment, ink is ejected out of a nozzle chamber viaan ink ejection port using a series of radially positioned thermalactuator devices that are arranged about the ink ejection port and areactivated to pressurize the ink within the nozzle chamber therebycausing the ejection of ink through the ejection port.

Turning now to FIGS. 1, 2 and 3, there is illustrated the basicoperational principles of the preferred embodiment. FIG. 1 illustrates asingle nozzle arrangement 1 in its quiescent state. The arrangement 1includes a nozzle chamber 2 which is normally filled with ink so as toform a meniscus 3 in an ink ejection port 4. The nozzle chamber 2 isformed within a wafer 5. The nozzle chamber 2 is supplied with ink viaan ink supply channel 6 which is etched through the wafer 5 with ahighly isotropic plasma etching system. A suitable etcher can be theAdvance Silicon Etch (ASE) system available from Surface TechnologySystems of the United Kingdom.

A top of the nozzle arrangement 1 includes a series of radiallypositioned actuators 8, 9. These actuators comprise apolytetrafluoroethylene (PTFE) layer and an internal serpentine coppercore 17. Upon heating of the copper core 17, the surrounding PTFEexpands rapidly resulting in a generally downward movement of theactuators 8, 9. Hence, when it is desired to eject ink from the inkejection port 4, a current is passed through the actuators 8, 9 whichresults in them bending generally downwards as illustrated in FIG. 2.The downward bending movement of the actuators 8, 9 results in asubstantial increase in pressure within the nozzle chamber 2. Theincrease in pressure in the nozzle chamber 2 results in an expansion ofthe meniscus 3 as illustrated in FIG. 2.

The actuators 8, 9 are activated only briefly and subsequentlydeactivated. Consequently, the situation is as illustrated in FIG. 3with the actuators 8, 9 returning to their original positions. Thisresults in a general inflow of ink back into the nozzle chamber 2 and anecking and breaking of the meniscus 3 resulting in the ejection of adrop 12. The necking and breaking of the meniscus 3 is a consequence ofthe forward momentum of the ink associated with drop 12 and the backwardpressure experienced as a result of the return of the actuators 8, 9 totheir original positions. The return of the actuators 8,9 also resultsin a general inflow of ink from the channel 6 as a result of surfacetension effects and, eventually, the state returns to the quiescentposition as illustrated in FIG. 1.

FIGS. 4(a) and 4(b) illustrate the principle of operation of the thermalactuator. The thermal actuator is preferably constructed from a material14 having a high coefficient of thermal expansion. Embedded within thematerial 14 are a series of heater elements 15 which can be a series ofconductive elements designed to carry a current. The conductive elements15 are heated by passing a current through the elements 15 with theheating resulting in a general increase in temperature in the areaaround the heating elements 15. The position of the elements 15 is suchthat uneven heating of the material 14 occurs. The uneven increase intemperature causes a corresponding uneven expansion of the material 14.Hence, as illustrated in FIG. 4(b), the PTFE is bent generally in thedirection shown.

In FIG. 5, there is illustrated a side perspective view of oneembodiment of a nozzle arrangement constructed in accordance with theprinciples previously outlined. The nozzle chamber 2 is formed with anisotropic surface etch of the wafer 5. The wafer 5 can include a CMOSlayer including all the required power and drive circuits. Further, theactuators 8, 9 each have a leaf or petal formation which extends towardsa nozzle rim 28 defining the ejection port 4. The normally inner end ofeach leaf or petal formation is displaceable with respect to the nozzlerim 28. Each activator 8, 9 has an internal copper core 17 defining theelement 15. The core 17 winds in a serpentine manner to provide forsubstantially unhindered expansion of the actuators 8, 9. The operationof the actuators 8, 9 is as illustrated in FIG. 4(a) and FIG. 4(b) suchthat, upon activation, the actuators 8 bend as previously describedresulting in a displacement of each petal formation away from the nozzlerim 28 and into the nozzle chamber 2. The ink supply channel 6 can becreated via a deep silicon back edge of the wafer 5 utilizing a plasmaetcher or the like. The copper or aluminium core 17 can provide acomplete circuit. A central arm 18 which can include both metal and PTFEportions provides the main structural support for the actuators 8, 9.

Turning now to FIG. 6 to FIG. 13, one form of manufacture of the nozzlearrangement 1 in accordance with the principles of the preferredembodiment is shown. The nozzle arrangement 1 is preferably manufacturedusing microelectromechanical (MEMS) techniques and can include thefollowing construction techniques:

As shown initially in FIG. 6, the initial processing starting materialis a standard semi-conductor wafer 20 having a complete CMOS level 21 toa first level of metal. The first level of metal includes portions 22which are utilized for providing power to the thermal actuators 8, 9.

The first step, as illustrated in FIG. 7, is to etch a nozzle regiondown to the silicon wafer 20 utilizing an appropriate mask.

Next, as illustrated in FIG. 8, a 2 μm layer of polytetrafluoroethylene(PTFE) is deposited and etched so as to define vias 24 forinterconnecting multiple levels.

Next, as illustrated in FIG. 9, the second level metal layer isdeposited, masked and etched to define a heater structure 25. The heaterstructure 25 includes via 26 interconnected with a lower aluminiumlayer.

Next, as illustrated in FIG. 10, a further 2 μm layer of PTFE isdeposited and etched to the depth of 1 μm utilizing a nozzle rim mask todefine the nozzle rim 28 in addition to ink flow guide rails 29 whichgenerally restrain any wicking along the surface of the PTFE layer. Theguide rails 29 surround small thin slots and, as such, surface tensioneffects are a lot higher around these slots which in turn results inminimal outflow of ink during operation.

Next, as illustrated in FIG. 11, the PTFE is etched utilizing a nozzleand actuator mask to define a port portion 30 and slots 31 and 32.

Next, as illustrated in FIG. 12, the wafer is crystallographicallyetched on a <111> plane utilizing a standard crystallographic etchantsuch as KOH. The etching forms a chamber 33, directly below the portportion 30.

In FIG. 13, the ink supply channel 34 can be etched from the back of thewafer utilizing a highly anisotropic etcher such as the STS etcher fromSilicon Technology Systems of United Kingdom. An array of ink jetnozzles can be formed simultaneously with a portion of an array 36 beingillustrated in FIG. 14. A portion of the printhead is formedsimultaneously and diced by the STS etching process. The array 36 shownprovides for four column printing with each separate column attached toa different colour ink supply channel being supplied from the back ofthe wafer. Bond pads 37 provide for electrical control of the ejectionmechanism.

In this manner, large pagewidth printheads can be fabricated so as toprovide for a drop-on-demand ink ejection mechanism.

One form of detailed manufacturing process which can be used tofabricate monolithic ink jet printheads operating in accordance with theprinciples taught by the present embodiment can proceed utilizing thefollowing steps:

1. Using a double-sided polished wafer 60, complete a 0.5 micron, onepoly, 2 metal CMOS process 61. This step is shown in FIG. 16. Forclarity, these diagrams may not be to scale, and may not represent across section though any single plane of the nozzle. FIG. 15 is a key torepresentations of various materials in these manufacturing diagrams,and those of other cross referenced ink jet configurations.

2. Etch the CMOS oxide layers down to silicon or second level metalusing Mask 1. This mask defines the nozzle cavity and the edge of thechips. This step is shown in FIG. 16.

3. Deposit a thin layer (not shown) of a hydrophilic polymer, and treatthe surface of this polymer for PTFE adherence.

4. Deposit 1.5 microns of polytetrafluoroethylene (PTFE) 62.

5. Etch the PTFE and CMOS oxide layers to second level metal using Mask2. This mask defines the contact vias for the heater electrodes. Thisstep is shown in FIG. 17.

6. Deposit and pattern 0.5 microns of gold 63 using a lift-off processusing Mask 3. This mask defines the heater pattern. This step is shownin FIG. 18.

7. Deposit 1.5 microns of PTFE 64.

8. Etch 1 micron of PTFE using Mask 4. This mask defines the nozzle rim65 and the rim at the edge 66 of the nozzle chamber. This step is shownin FIG. 19.

9. Etch both layers of PTFE and the thin hydrophilic layer down tosilicon using Mask 5. This mask defines a gap 67 at inner edges of theactuators, and the edge of the chips. It also forms the mask for asubsequent crystallographic etch. This step is shown in FIG. 20.

10. Crystallographically etch the exposed silicon using KOH. This etchstops on <111> crystallographic planes 68, forming an inverted squarepyramid with sidewall angles of 54.74 degrees. This step is shown inFIG. 21.

11. Back-etch through the silicon wafer (with, for example, an ASEAdvanced Silicon Etcher from Surface Technology Systems) using Mask 6.This mask defines the ink inlets 69 which are etched through the wafer.The wafer is also diced by this etch. This step is shown in FIG. 22.

12. Mount the printheads in their packaging, which may be a moldedplastic former incorporating ink channels which supply the appropriatecolor ink to the ink inlets 69 at the back of the wafer.

13. Connect the printheads to their interconnect systems. For a lowprofile connection with minimum disruption of airflow, TAB may be used.Wire bonding may also be used if the printer is to be operated withsufficient clearance to the paper.

14. Fill the completed print heads with ink 70 and test them. A fillednozzle is shown in FIG. 23.

The presently disclosed ink jet printing technology is potentiallysuited to a wide range of printing systems including: color andmonochrome office printers, short run digital printers, high speeddigital printers, offset press supplemental printers, low cost scanningprinters high speed pagewidth printers, notebook computers with inbuiltpagewidth printers, portable color and monochrome printers, color andmonochrome copiers, color and monochrome facsimile machines, combinedprinter, facsimile and copying machines, label printers, large formatplotters, photograph copiers, printers for digital photographic“minilabs”, video printers, PHOTO CD (PHOTO CD is a registered trademark of the Eastman Kodak Company) printers, portable printers for PDAs,wallpaper printers, indoor sign printers, billboard printers, fabricprinters, camera printers and fault tolerant commercial printer arrays.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects to be illustrative andnot restrictive.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Ofcourse many different devices could be used. However presently popularink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption.This is approximately 100 times that required for high speed, and stemsfrom the energy-inefficient means of drop ejection. This involves therapid boiling of water to produce a vapor bubble which expels the ink.Water has a very high heat capacity, and must be superheated in thermalink jet applications. This leads to an efficiency of around 0.02%, fromelectricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size andcost. Piezoelectric crystals have a very small deflection at reasonabledrive voltages, and therefore require a large area for each nozzle.Also, each piezoelectric actuator must be connected to its drive circuiton a separate substrate. This is not a significant problem at thecurrent limit of around 300 nozzles per printhead, but is a majorimpediment to the fabrication of pagewidth printheads with 19,200nozzles.

Ideally, the ink jet technologies used meet the stringent requirementsof in-camera digital color printing and other high quality, high speed,low cost printing applications. To meet the requirements of digitalphotography, new ink jet technologies have been created. The targetfeatures include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systemsdescribed below with differing levels of difficulty. Forty-fivedifferent ink jet technologies have been developed by the Assignee togive a wide range of choices for high volume manufacture. Thesetechnologies form part of separate applications assigned to the presentAssignee as set out in the table below under the heading CrossReferences to Related Applications.

The ink jet designs shown here are suitable for a wide range of digitalprinting systems, from battery powered one-time use digital cameras,through to desktop and network printers, and through to commercialprinting systems.

For ease of manufacture using standard process equipment, the printheadis designed to be a monolithic 0.5 micron CMOS chip with MEMS postprocessing. For color photographic applications, the printhead is 100 mmlong, with a width which depends upon the ink jet type. The smallestprinthead designed is IJ38, which is 0.35 mm wide, giving a chip area of35 square mm. The printheads each contain 19,200 nozzles plus data andcontrol circuitry.

Ink is supplied to the back of the printhead by injection molded plasticink channels. The molding requires 50 micron features, which can becreated using a lithographically micromachined insert in a standardinjection molding tool. Ink flows through holes etched through the waferto the nozzle chambers fabricated on the front surface of the wafer. Theprinthead is connected to the camera circuitry by tape automatedbonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation ofindividual ink jet nozzles have been identified. These characteristicsare largely orthogonal, and so can be elucidated as an elevendimensional matrix. Most of the eleven axes of this matrix includeentries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains36.9 billion possible configurations of ink jet nozzle. While not all ofthe possible combinations result in a viable ink jet technology, manymillion configurations are viable. It is clearly impractical toelucidate all of the possible configurations. Instead, certain ink jettypes have been investigated in detail. These are designated IJ01 toIJ45 above which matches the docket numbers in the table under theheading Cross References to Related Applications.

Other ink jet configurations can readily be derived from theseforty-five examples by substituting alternative configurations along oneor more of the 11 axes. Most of the IJ01 to IJ45 examples can be madeinto ink jet printheads with characteristics superior to any currentlyavailable ink jet technology.

Where there are prior art examples known to the inventor, one or more ofthese examples are listed in the examples column of the tables below.The IJ01 to IJ45 series are also listed in the examples column. In somecases, print technology may be listed more than once in a table, whereit shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Homeprinters, Office network printers, Short run digital printers,Commercial print systems, Fabric printers, Pocket printers, Internet WWWprinters, Video printers, Medical imaging, Wide format printers,Notebook PC printers, Fax machines, Industrial printing systems,Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrixare set out in the following tables. ACTUATOR MECHANISM (APPLIED ONLY TOSELECTED INK DROPS) Description Advantages Disadvantages ExamplesThermal An electrothermal Large force High power Canon bubble heaterheats the generated Ink carrier Bubblejet 1979 ink to above Simplelimited to water Endo et al GB boiling point, construction Low patent2,007,162 transferring No moving efficiency Xerox heater- significantheat to parts High in-pit 1990 the aqueous ink. A Fast operationtemperatures Hawkins et al bubble nucleates Small chip required U.S.Pat. No. 4,899,181 and quickly forms, area required for High Hewlett-expelling the ink. actuator mechanical Packard TIJ The efficiency ofstress 1982 Vaught et the process is low, Unusual al U.S. Pat. No. withtypically less materials 4,490,728 than 0.05% of the required electricalenergy Large drive being transformed transistors into kinetic energyCavitation of the drop. causes actuator failure Kogation reduces bubbleformation Large print heads are difficult to fabricate Piezoelectric Apiezoelectric Low power Very large Kyser et al crystal such asconsumption area required for U.S. Pat. No. 3,946,398 lead lanthanumMany ink actuator Zoltan U.S. Pat. No. zirconate (PZT) is types can beDifficult to 3,683,212 electrically used integrate with 1973 Stemmeactivated, and Fast operation electronics U.S. Pat. No. 3,747,120 eitherexpands, High High voltage Epson Stylus shears, or bends to efficiencydrive transistors Tektronix apply pressure to required IJ04 the ink,ejecting Full drops. pagewidth print heads impractical due to actuatorsize Requires electrical poling in high field strengths duringmanufacture Electrostrictive An electric field is Low power Low SeikoEpson, used to activate consumption maximum strain Usui et all JPelectrostriction in Many ink (approx. 0.01%) 253401/96 relaxor materialstypes can be Large area IJ04 such as lead used required for lanthanumLow thermal actuator due to zirconate titanate expansion low strain(PLZT) or lead Electric field Response magnesium strength required speedis niobate (PMN). (approx. 3.5 V/μm) marginal (˜10 μs) can be Highvoltage generated drive transistors without required difficulty FullDoes not pagewidth print require electrical heads poling impractical dueto actuator size Ferroelectric An electric field is Low power Difficultto IJ04 used to induce a consumption integrate with phase transitionMany ink electronics between the types can be Unusual antiferroelectricused materials such as (AFE) and Fast operation PLZSnT are ferroelectric(FE) (<1 μs) required phase. Perovskite Relatively Actuators materialssuch as high longitudinal require a large tin modified lead strain arealanthanum High zirconate titanate efficiency (PLZSnT) exhibit Electricfield large strains of up strength of to 1% associated around 3 V/μmwith the AFE to can be readily FE phase provided transition.Electrostatic Conductive plates Low power Difficult to IJ02, IJ04 platesare separated by a consumption operate compressible or Many inkelectrostatic fluid dielectric types can be devices in an (usually air).Upon used aqueous application of a Fast operation environment voltage,the plates The attract each other electrostatic and displace ink,actuator will causing drop normally need to ejection. The be separatedconductive plates from the ink may be in a comb Very large or honeycombarea required to structure, or achieve high stacked to increase forcesthe surface area High voltage and therefore the drive transistors force.may be required Full pagewidth print heads are not competitive due toactuator size Electrostatic A strong electric Low current High voltage1989 Saito et pull field is applied to consumption required al, U.S.Pat. No. on ink the ink, whereupon Low May be 4,799,068 electrostatictemperature damaged by 1989 Miura et attraction sparks due to air al,U.S. Pat. No. accelerates the ink breakdown 4,810,954 towards the printRequired field Tone-jet medium. strength increases as the drop sizedecreases High voltage drive transistors required Electrostatic fieldattracts dust Permanent An electromagnet Low power Complex IJ07, IJ10magnet directly attracts a consumption fabrication electromagneticpermanent magnet, Many ink Permanent displacing ink and types can bemagnetic causing drop used material such as ejection. Rare Fastoperation Neodymium Iron earth magnets with High Boron (NdFeB) a fieldstrength efficiency required. around 1 Tesla can Easy High local beused. Examples extension from currents required are: Samarium singlenozzles to Copper Cobalt (SaCo) and pagewidth print metalizationmagnetic materials heads should be used in the neodymium for long ironboron family electromigration (NdFeB, lifetime and low NdDyFeBNb,resistivity NdDyFeB, etc) Pigmented inks are usually infeasibleOperating temperature limited to the Curie temperature (around 540 K)Soft A solenoid Low power Complex IJ01, IJ05, magnetic induced aconsumption fabrication IJ08, IJ10, IJ12, core magnetic field in a Manyink Materials not IJ14, IJ15, IJ17 electromagnetic soft magnetic coretypes can be usually present or yoke fabricated used in a CMOS fab froma ferrous Fast operation such as NiFe, material such as High CoNiFe, orCoFe electroplated iron efficiency are required alloys such as Easy Highlocal CoNiFe [1], CoFe, extension from currents required or NiFe alloys.single nozzles to Copper Typically, the soft pagewidth printmetalization magnetic material heads should be used is in two parts, forlong which are electromigration normally held lifetime and low apart bya spring. resistivity When the solenoid Electroplating is actuated, thetwo is required parts attract, High displacing the ink. saturation fluxdensity is required (2.0-2.1 T is achievable with CoNiFe [1]) Lorenz TheLorenz force Low power Force acts as a IJ06, IJ11, force acting on acurrent consumption twisting motion IJ13, IJ16 carrying wire in a Manyink Typically, magnetic field is types can be only a quarter ofutilized. used the solenoid This allows the Fast operation lengthprovides magnetic field to High force in a useful be supplied efficiencydirection externally to the Easy High local print head, for extensionfrom currents required example with rare single nozzles to Copper earthpermanent pagewidth print metalization magnets. heads should be usedOnly the current for long carrying wire need electromigration befabricated on lifetime and low the print-head, resistivity simplifyingPigmented materials inks are usually requirements. infeasibleMagnetostriction The actuator uses Many ink Force acts as a Fischenbeck,the giant types can be twisting motion U.S. Pat. No. 4,032,929magnetostrictive used Unusual IJ25 effect of materials Fast operationmaterials such as such as Terfenol-D Easy Terfenol-D are (an alloy ofextension from required terbium, single nozzles to High local dysprosiumand pagewidth print currents required iron developed at heads Copper theNaval High force is metalization Ordnance available should be usedLaboratory, hence for long Ter-Fe-NOL). For electromigration bestefficiency, the lifetime and low actuator should be resistivitypre-stressed to Pre-stressing approx. 8 MPa. may be required Surface Inkunder positive Low power Requires Silverbrook, tension pressure is heldin consumption supplementary EP 0771 658 A2 reduction a nozzle bysurface Simple force to effect and related tension. The constructiondrop separation patent surface tension of No unusual Requiresapplications the ink is reduced materials special ink below the bubblerequired in surfactants threshold, causing fabrication Speed may be theink to egress High limited by from the nozzle. efficiency surfactantEasy properties extension from single nozzles to pagewidth print headsViscosity The ink viscosity Simple Requires Silverbrook, reduction islocally reduced construction supplementary EP 0771 658 A2 to selectwhich No unusual force to effect and related drops are to be materialsdrop separation patent ejected. A required in Requires applicationsviscosity reduction fabrication special ink can be achieved Easyviscosity electrothermally extension from properties with most inks, butsingle nozzles to High speed is special inks can be pagewidth printdifficult to engineered for a heads achieve 100:1 viscosity Requiresreduction. oscillating ink pressure A high temperature difference(typically 80 degrees) is required Acoustic An acoustic wave Can operateComplex 1993 is generated and without a nozzle drive circuitryHadimioglu et focussed upon the plate Complex al, EUP 550,192 dropejection fabrication 1993 Elrod et region. Low al, EUP 572,220efficiency Poor control of drop position Poor control of drop volumeThermoelastic An actuator which Low power Efficient IJ03, IJ09, bendrelies upon consumption aqueous IJ17, IJ18, IJ19, actuator differentialMany ink operation IJ20, IJ21, IJ22, thermal expansion types can berequires a IJ23, IJ24, IJ27, upon Joule heating used thermal insulatorIJ28, IJ29, IJ30, is used. Simple planar on the hot side IJ31, IJ32,IJ33, fabrication Corrosion IJ34, IJ35, IJ36, Small chip prevention canIJ37, IJ38, IJ39, area required for be difficult IJ40, IJ41 eachactuator Pigmented Fast operation inks may be High infeasible, asefficiency pigment particles CMOS may jam the compatible bend actuatorvoltages and currents Standard MEMS processes can be used Easy extensionfrom single nozzles to pagewidth print heads High CTE A material with aHigh force Requires IJ09, IJ17, thermoelastic very high can be generatedspecial material IJ18, IJ20, IJ21, actuator coefficient of Three (e.g.PTFE) IJ22, IJ23, IJ24, thermal expansion methods of Requires a IJ27,IJ28, IJ29, (CTE) such as PTFE deposition PTFE deposition IJ30, IJ31,IJ42, polytetrafluoroethylene are under process, which is IJ43, IJ44(PTFE) is development: not yet standard used. As high CTE chemical vaporin ULSI fabs materials are deposition PTFE usually non- (CVD), spindeposition conductive, a coating, and cannot be heater fabricatedevaporation followed with from a conductive PTFE is a high temperaturematerial is candidate for (above 350° C.) incorporated. A 50 μm lowdielectric processing long PTFE constant Pigmented bend actuator withinsulation in inks may be polysilicon heater ULSI infeasible, as and 15mW power Very low pigment particles input can provide power may jam the180 μN force and consumption bend actuator 10 μm deflection. Many inkActuator motions types can be include: used Bend Simple planar Pushfabrication Buckle Small chip Rotate area required for each actuatorFast operation High efficiency CMOS compatible voltages and currentsEasy extension from single nozzles to pagewidth print heads Conductive Apolymer with a High force Requires IJ24 polymer high coefficient of canbe generated special materials thermoelastic thermal expansion Very lowdevelopment actuator (such as PTFE) is power (High CTE doped withconsumption conductive conducting Many ink polymer) substances to typescan be Requires a increase its used PTFE deposition conductivity toSimple planar process, which is about 3 orders of fabrication not yetstandard magnitude below Small chip in ULSI fabs that of copper. Thearea required for PTFE conducting each actuator deposition polymerexpands Fast operation cannot be when resistively High followed withheated. efficiency high temperature Examples of CMOS (above 350° C.)conducting compatible processing dopants include: voltages andEvaporation Carbon nanotubes currents and CVD Metal fibers Easydeposition Conductive extension from techniques polymers such as singlenozzles to cannot be used doped pagewidth print Pigmented polythiopheneheads inks may be Carbon granules infeasible, as pigment particles mayjam the bend actuator Shape A shape memory High force is Fatigue limitsIJ26 memory alloy such as TiNi available maximum alloy (also known as(stresses of number of cycles Nitinol —Nickel hundreds of Low strainTitanium alloy MPa) (1%) is required developed at the Large strain is toextend fatigue Naval Ordnance available (more resistance Laboratory) isthan 3%) Cycle rate thermally switched High limited by heat between itsweak corrosion removal martensitic state resistance Requires and itshigh Simple unusual stiffness austenic construction materials (TiNi)state. The shape of Easy The latent the actuator in its extension fromheat of martensitic state is single nozzles to transformation deformedrelative pagewidth print must be to the austenic heads provided shape.The shape Low voltage High current change causes operation operationejection of a drop. Requires pre- stressing to distort the martensiticstate Linear Linear magnetic Linear Requires IJ12 Magnetic actuatorsinclude Magnetic unusual Actuator the Linear actuators can besemiconductor Induction Actuator constructed with materials such as(LIA), Linear high thrust, long soft magnetic Permanent Magnet travel,and high alloys (e.g. Synchronous efficiency using CoNiFe) Actuatorplanar Some varieties (LPMSA), Linear semiconductor also requireReluctance fabrication permanent Synchronous techniques magneticActuator (LRSA), Long actuator materials such as Linear Switched travelis Neodymium iron Reluctance available boron (NdFeB) Actuator (LSRA),Medium force Requires and the Linear is available complex multi- StepperActuator Low voltage phase drive (LSA). operation circuitry High currentoperation

BASIC OPERATION MODE Description Advantages Disadvantages ExamplesActuator This is the Simple Drop Thermal ink directly simplest mode ofoperation repetition rate is jet pushes operation: the No externalusually limited Piezoelectric ink actuator directly fields required toaround 10 kHz. ink jet supplies sufficient Satellite drops However,IJ01, IJ02, kinetic energy to can be avoided if this is not IJ03, IJ04,IJ05, expel the drop. drop velocity is fundamental to IJ06, IJ07, IJ09,The drop must less than 4 m/s the method, but IJ11, IJ12, IJ14, have asufficient Can be is related to the IJ16, IJ20, IJ22, velocity toefficient, refill method IJ23, IJ24, IJ25, overcome the depending uponnormally used IJ26, IJ27, IJ28, surface tension. the actuator used Allof the drop IJ29, IJ30, IJ31, kinetic energy IJ32, IJ33, IJ34, must beIJ35, IJ36, IJ37, provided by the IJ38, IJ39, IJ40, actuator IJ41, IJ42,IJ43, Satellite drops IJ44 usually form if drop velocity is greater than4.5 m/s Proximity The drops to be Very simple Requires closeSilverbrook, printed are print head proximity EP 0771 658 A2 selected bysome fabrication can between the and related manner (e.g. be used printhead and patent thermally induced The drop the print media applicationssurface tension selection means or transfer roller reduction of does notneed to May require pressurized ink). provide the two print headsSelected drops are energy required printing alternate separated from theto separate the rows of the ink in the nozzle drop from the image bycontact with the nozzle Monolithic print medium or a color print headstransfer roller. are difficult Electrostatic The drops to be Very simpleRequires very Silverbrook, pull printed are print head highelectrostatic EP 0771 658 A2 on ink selected by some fabrication canfield and related manner (e.g. be used Electrostatic patent thermallyinduced The drop field for small applications surface tension selectionmeans nozzle sizes is Tone-Jet reduction of does not need to above airpressurized ink). provide the breakdown Selected drops are energyrequired Electrostatic separated from the to separate the field mayattract ink in the nozzle drop from the dust by a strong electric nozzlefield. Magnetic The drops to be Very simple Requires Silverbrook, pullon printed are print head magnetic ink EP 0771 658 A2 ink selected bysome fabrication can Ink colors and related manner (e.g. be used otherthan black patent thermally induced The drop are difficult applicationssurface tension selection means Requires very reduction of does not needto high magnetic pressurized ink). provide the fields Selected drops areenergy required separated from the to separate the ink in the nozzledrop from the by a strong nozzle magnetic field acting on the magneticink. Shutter The actuator High speed Moving parts IJ13, IJ17, moves ashutter to (>50 kHz) are required IJ21 block ink flow to operation canbe Requires ink the nozzle. The ink achieved due to pressure pressure ispulsed reduced refill modulator at a multiple of the time Friction anddrop ejection Drop timing wear must be frequency. can be very consideredaccurate Stiction is The actuator possible energy can be very lowShuttered The actuator Actuators with Moving parts IJ08, IJ15, grillmoves a shutter to small travel can are required IJ18, IJ19 block inkflow be used Requires ink through a grill to Actuators with pressure thenozzle. The small force can modulator shutter movement be used Frictionand need only be equal High speed wear must be to the width of the (>50kHz) considered grill holes. operation can be Stiction is achievedpossible Pulsed A pulsed magnetic Extremely low Requires an IJ10magnetic field attracts an energy operation external pulsed pull on ‘inkpusher’ at the is possible magnetic field ink drop ejection No heatRequires pusher frequency. An dissipation special materials actuatorcontrols a problems for both the catch, which actuator and the preventsthe ink ink pusher pusher from Complex moving when a construction dropis not to be ejected.

Description Advantages Disadvantages Examples AUXILIARY MECHANISM(APPLIED TO ALL NOZZLES) None The actuator Simplicity of Drop ejectionMost ink jets, directly fires the construction energy must be includingink drop, and there Simplicity of supplied by piezoelectric and is noexternal field operation individual nozzle thermal bubble. or otherSmall physical actuator IJ01, IJ02, mechanism size IJ03, IJ04, IJ05,required. IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24, IJ25,IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36, IJ37,IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The ink pressureOscillating ink Requires Silverbrook, ink oscillates, pressure canexternal ink EP 0771 658 A2 pressure providing much of provide a refillpressure and related (including the drop ejection pulse, allowingoscillator patent acoustic energy. The higher operating Ink pressureapplications stimulation) actuator selects speed phase and IJ08, IJ13,which drops are to The actuators amplitude must IJ15, IJ17, IJ18, befired by may operate be carefully IJ19, IJ21 selectively with much lowercontrolled blocking or energy Acoustic enabling nozzles. Acousticreflections in the The ink pressure lenses can be ink chamberoscillation may be used to focus the must be achieved by sound on thedesigned for vibrating the print nozzles head, or preferably by anactuator in the ink supply. Media The print head is Low power PrecisionSilverbrook, proximity placed in close High accuracy assembly EP 0771658 A2 proximity to the Simple print required and related print medium.head Paper fibers patent Selected drops construction may causeapplications protrude from the problems print head further Cannot printthan unselected on rough drops, and contact substrates the print medium.The drop soaks into the medium fast enough to cause drop separation.Transfer Drops are printed High accuracy Bulky Silverbrook, roller to atransfer roller Wide range of Expensive EP 0771 658 A2 instead ofstraight print substrates Complex and related to the print can be usedconstruction patent medium. A Ink can be applications transfer rollercan dried on the Tektronix hot also be used for transfer roller meltproximity drop piezoelectric ink separation. jet Any of the IJ seriesElectrostatic An electric field is Low power Field strength Silverbrook,used to accelerate Simple print required for EP 0771 658 A2 selecteddrops head separation of and related towards the print constructionsmall drops is patent medium. near or above air applications breakdownTone-Jet Direct A magnetic field is Low power Requires Silverbrook,magnetic used to accelerate Simple print magnetic ink EP 0771 658 A2field selected drops of head Requires and related magnetic inkconstruction strong magnetic patent towards the print field applicationsmedium. Cross The print head is Does not Requires IJ06, IJ16 magneticplaced in a require magnetic external magnet field constant magneticmaterials to be Current field. The Lorenz integrated in the densitiesmay be force in a current print head high, resulting in carrying wire ismanufacturing electromigration used to move the process problemsactuator. Pulsed A pulsed magnetic Very low Complex print IJ10 magneticfield is used to power operation head field cyclically attract a ispossible construction paddle, which Small print Magnetic pushes on theink. head size materials A small actuator required in print moves acatch, head which selectively prevents the paddle from moving. ACTUATORAMPLIFICATION OR MODIFICATION METHOD None No actuator Operational Manyactuator Thermal mechanical simplicity mechanisms Bubble Ink jetamplification is have insufficient IJ01, IJ02, used. The actuatortravel, or IJ06, IJ07, IJ16, directly drives the insufficient IJ25, IJ26drop ejection force, to process. efficiently drive the drop ejectionprocess Differential An actuator Provides High stresses Piezoelectricexpansion material expands greater travel in are involved IJ03, IJ09,bend more on one side a reduced print Care must be IJ17, IJ18, IJ19,actuator than on the other. head area taken that the IJ20, IJ21, IJ22,The expansion materials do not IJ23, IJ24, IJ27, may be thermal,delaminate IJ29, IJ30, IJ31, piezoelectric, Residual bend IJ32, IJ33,IJ34, magnetostrictive, resulting from IJ35, IJ36, IJ37, or other hightemperature IJ38, IJ39, IJ42, mechanism. The or high stress IJ43, IJ44bend actuator during formation converts a high force low travel actuatormechanism to high travel, lower force mechanism. Transient A trilayerbend Very good High stresses IJ40, IJ41 bend actuator where thetemperature are involved actuator two outside layers stability Care mustbe are identical. This High speed, as taken that the cancels bend due anew drop can materials do not to ambient be fired before delaminatetemperature and heat dissipates residual stress. The Cancels actuatoronly residual stress of responds to formation transient heating of oneside or the other. Reverse The actuator loads Better Fabrication IJ05,IJ11 spring a spring. When the coupling to the complexity actuator isturned ink High stress in off, the spring the spring releases. This canreverse the force/distance curve of the actuator to make it compatiblewith the force/time requirements of the drop ejection. Actuator A seriesof thin Increased Increased Some stack actuators are travel fabricationpiezoelectric ink stacked. This can Reduced drive complexity jets beappropriate voltage Increased IJ04 where actuators possibility ofrequire high short circuits due electric field to pinholes strength,such as electrostatic and piezoelectric actuators. Multiple Multiplesmaller Increases the Actuator IJ12, IJ13, actuators actuators are usedforce available forces may not IJ18, IJ20, IJ22, simultaneously to froman actuator add linearly, IJ28, IJ42, IJ43 move the ink. Each Multiplereducing actuator need actuators can be efficiency provide only apositioned to portion of the control ink flow force required. accuratelyLinear A linear spring is Matches low Requires print IJ15 Spring used totransform a travel actuator head area for the motion with small withhigher spring travel and high travel force into a longer requirementstravel, lower force Non-contact motion. method of motion transformationCoiled A bend actuator is Increases Generally IJ17, IJ21, actuatorcoiled to provide travel restricted to IJ34, IJ35 greater travel in aReduces chip planar reduced chip area. area implementations Planar dueto extreme implementations fabrication are relatively difficulty in easyto fabricate. other orientations. Flexure A bend actuator Simple meansCare must be IJ10, IJ19, bend has a small region of increasing taken notto IJ33 actuator near the fixture travel of a bend exceed the point,which flexes actuator elastic limit in much more readily the flexurearea than the remainder Stress of the actuator. distribution is Theactuator very uneven flexing is Difficult to effectively accuratelymodel converted from an with finite even coiling to an element analysisangular bend, resulting in greater travel of the actuator tip. Catch Theactuator Very low Complex IJ10 controls a small actuator energyconstruction catch. The catch Very small Requires either enables oractuator size external force disables movement Unsuitable for of an inkpusher pigmented inks that is controlled in a bulk manner. Gears Gearscan be used Low force, Moving parts IJ13 to increase travel low travelare required at the expense of actuators can be Several duration.Circular used actuator cycles gears, rack and Can be are requiredpinion, ratchets, fabricated using More complex and other gearingstandard surface drive electronics methods can be MEMS Complex used.processes construction Friction, friction, and wear are possible BuckleA buckle plate can Very fast Must stay S. Hirata et al, plate be used tochange movement within elastic “An Ink-jet a slow actuator achievablelimits of the Head Using into a fast motion. materials for Diaphragm Itcan also convert long device life Microactuator”, a high force, low Highstresses Proc. IEEE travel actuator into involved MEMS, February a hightravel, Generally 1996, pp 418-423. medium force high power IJ18, IJ27motion. requirement Tapered A tapered Linearizes the Complex IJ14magnetic magnetic pole can magnetic construction pole increase travel atforce/distance the expense of curve force. Lever A lever and Matches lowHigh stress IJ32, IJ36, fulcrum is used to travel actuator around theIJ37 transform a motion with higher fulcrum with small travel travel andhigh force into requirements a motion with Fulcrum area longer traveland has no linear lower force. The movement, and lever can also can beused for a reverse the fluid seal direction of travel. Rotary Theactuator is High Complex IJ28 impeller connected to a mechanicalconstruction rotary impeller. A advantage Unsuitable for small angularThe ratio of pigmented inks deflection of the force to travel ofactuator results in the actuator can a rotation of the be matched toimpeller vanes, the nozzle which push the ink requirements by againststationary varying the vanes and out of number of the nozzle. impellervanes Acoustic A refractive or No moving Large area 1993 lensdiffractive (e.g. parts required Hadimioglu et zone plate) Only relevantal, EUP 550,192 acoustic lens is for acoustic ink 1993 Elrod et used toconcentrate jets al, EUP 572,220 sound waves. Sharp A sharp point isSimple Difficult to Tone-jet conductive used to concentrate constructionfabricate using point an electrostatic standard VLSI field. processesfor a surface ejecting ink-jet Only relevant for electrostatic ink jets

ACTUATOR MOTION Description Advantages Disadvantages Examples Volume Thevolume of the Simple High energy is Hewlett- expansion actuator changes,construction in typically Packard Thermal pushing the ink in the case ofrequired to Ink jet all directions. thermal ink jet achieve volume Canonexpansion. This Bubblejet leads to thermal stress, cavitation, andkogation in thermal ink jet implementations Linear, The actuatorEfficient High IJ01, IJ02, normal to moves in a coupling to inkfabrication IJ04, IJ07, IJ11, chip direction normal to drops ejectedcomplexity may IJ14 surface the print head normal to the be required tosurface. The surface achieve nozzle is typically perpendicular in theline of motion movement. Parallel to The actuator Suitable forFabrication IJ12, IJ13, chip moves parallel to planar complexity IJ15,IJ33,, IJ34, surface the print head fabrication Friction IJ35, IJ36surface. Drop Stiction ejection may still be normal to the surface.Membrane An actuator with a The effective Fabrication 1982 Howkins pushhigh force but area of the complexity U.S. Pat. No. 4,459,601 small areais used actuator Actuator size to push a stiff becomes the Difficulty ofmembrane that is membrane area integration in a in contact with the VLSIprocess ink. Rotary The actuator Rotary levers Device IJ05, IJ08, causesthe rotation may be used to complexity IJ13, IJ28 of some element,increase travel May have such a grill or Small chip friction at a pivotimpeller area point requirements Bend The actuator bends A very smallRequires the 1970 Kyser et when energized. change in actuator to be alU.S. Pat. No. This may be due to dimensions can made from at 3,946,398differential be converted to a least two distinct 1973 Stemme thermalexpansion, large motion. layers, or to have U.S. Pat. No. 3,747,120piezoelectric a thermal IJ03, IJ09, expansion, difference across IJ10,IJ19, IJ23, magnetostriction, the actuator IJ24, IJ25, IJ29, or otherform of IJ30, IJ31, IJ33, relative IJ34, IJ35 dimensional change. SwivelThe actuator Allows Inefficient IJ06 swivels around a operation wherecoupling to the central pivot. This the net linear ink motion motion issuitable force on the where there are paddle is zero opposite forcesSmall chip applied to opposite area sides of the paddle, requirementse.g. Lorenz force. Straighten The actuator is Can be used Requires IJ26,IJ32 normally bent, and with shape careful balance straightens whenmemory alloys of stresses to energized. where the ensure that theaustenic phase is quiescent bend is planar accurate Double The actuatorbends One actuator Difficult to IJ36, IJ37, bend in one direction can beused to make the drops IJ38 when one element power two ejected by bothis energized, and nozzles. bend directions bends the other Reduced chipidentical. way when another size. A small element is Not sensitiveefficiency loss energized. to ambient compared to temperature equivalentsingle bend actuators. Shear Energizing the Can increase Not readily1985 Fishbeck actuator causes a the effective applicable to U.S. Pat.No. 4,584,590 shear motion in the travel of other actuator actuatormaterial. piezoelectric mechanisms actuators Radial The actuatorRelatively High force 1970 Zoltan constriction squeezes an ink easy tofabricate required U.S. Pat. No. 3,683,212 reservoir, forcing singlenozzles Inefficient ink from a from glass Difficult to constrictednozzle. tubing as integrate with macroscopic VLSI processes structuresCoil/ A coiled actuator Easy to Difficult to IJ17, IJ21, uncoil uncoilsor coils fabricate as a fabricate for IJ34, IJ35 more tightly. Theplanar VLSI non-planar motion of the free process devices end of theactuator Small area Poor out-of- ejects the ink. required, planestiffness therefore low cost Bow The actuator bows Can increase MaximumIJ16, IJ18, (or buckles) in the the speed of travel is IJ27 middle whentravel constrained energized. Mechanically High force rigid requiredPush-Pull Two actuators The structure Not readily IJ18 control ashutter. is pinned at both suitable for ink One actuator pulls ends, sohas a jets which the shutter, and the high out-of- directly push theother pushes it. plane rigidity ink Curl A set of actuators Good fluidDesign IJ20, IJ42 inwards curl inwards to flow to the complexity reducethe volume region behind of ink that they the actuator enclose.increases efficiency Curl A set of actuators Relatively Relatively IJ43outwards curl outwards, simple large chip area pressurizing ink inconstruction a chamber surrounding the actuators, and expelling ink froma nozzle in the chamber. Iris Multiple vanes High High IJ22 enclose avolume efficiency fabrication of ink. These Small chip complexitysimultaneously area Not suitable rotate, reducing for pigmented thevolume inks between the vanes. Acoustic The actuator The actuator Largearea 1993 vibration vibrates at a high can be required for Hadimioglu etfrequency. physically efficient al, EUP 550,192 distant from theoperation at 1993 Elrod et ink useful al, EUP 572,220 frequenciesAcoustic coupling and crosstalk Complex drive circuitry Poor control ofdrop volume and position None In various ink jet No moving Various otherSilverbrook, designs the parts tradeoffs are EP 0771 658 A2 actuatordoes not required to and related move. eliminate patent moving partsapplications Tone-jet

NOZZLE REFILL METHOD Description Advantages Disadvantages ExamplesSurface This is the normal Fabrication Low speed Thermal ink tension waythat ink jets simplicity Surface jet are refilled. After Operationaltension force Piezoelectric the actuator is simplicity relatively smallink jet energized, it compared to IJ01-IJ07, typically returns actuatorforce IJ10-IJ14, IJ16, rapidly to its Long refill IJ20, IJ22-IJ45 normalposition. time usually This rapid return dominates the sucks in airtotal repetition through the nozzle rate opening. The ink surfacetension at the nozzle then exerts a small force restoring the meniscusto a minimum area. This force refills the nozzle. Shuttered Ink to thenozzle High speed Requires IJ08, IJ13, oscillating chamber is Lowactuator common ink IJ15, IJ17, IJ18, ink provided at a energy, as thepressure IJ19, IJ21 pressure pressure that actuator need oscillatoroscillates at twice only open or May not be the drop ejection close theshutter, suitable for frequency. When a instead of pigmented inks dropis to be ejecting the ink ejected, the shutter drop is opened for 3 halfcycles: drop ejection, actuator return, and refill. The shutter is thenclosed to prevent the nozzle chamber emptying during the next negativepressure cycle. Refill After the main High speed, as Requires two IJ09actuator actuator has the nozzle is independent ejected a drop aactively refilled actuators per second (refill) nozzle actuator isenergized. The refill actuator pushes ink into the nozzle chamber. Therefill actuator returns slowly, to prevent its return from emptying thechamber again. Positive The ink is held a High refill Surface spillSilverbrook, ink slight positive rate, therefore a must be EP 0771 658A2 pressure pressure. After the high drop prevented and related ink dropis ejected, repetition rate is Highly patent the nozzle possiblehydrophobic applications chamber fills print head Alternative quickly assurface surfaces are for:, IJ01-IJ07, tension and ink requiredIJ10-IJ14, IJ16, pressure both IJ20, IJ22-IJ45 operate to refill thenozzle.

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description AdvantagesDisadvantages Examples Long inlet The ink inlet Design Restricts refillThermal ink channel channel to the simplicity rate jet nozzle chamber isOperational May result in Piezoelectric made long and simplicity arelatively large ink jet relatively narrow, Reduces chip area IJ42, IJ43relying on viscous crosstalk Only partially drag to reduce effectiveinlet back-flow. Positive The ink is under a Drop selection Requires aSilverbrook, ink positive pressure, and separation method (such as EP0771 658 A2 pressure so that in the forces can be a nozzle rim or andrelated quiescent state reduced effective patent some of the ink Fastrefill time hydrophobizing, applications drop already or both) toPossible protrudes from the prevent flooding operation of the nozzle. ofthe ejection following: IJ01-IJ07, This reduces the surface of theIJ09-IJ12, pressure in the print head. IJ14, IJ16, IJ20, nozzle chamberIJ22,, IJ23-IJ34, which is required IJ36-IJ41, IJ44 to eject a certainvolume of ink. The reduction in chamber pressure results in a reductionin ink pushed out through the inlet. Baffle One or more The refill rateDesign HP Thermal baffles are placed is not as complexity Ink Jet in theinlet ink restricted as the May increase Tektronix flow. When the longinlet fabrication piezoelectric ink actuator is method. complexity (e.g.jet energized, the Reduces Tektronix hot rapid ink crosstalk meltmovement creates Piezoelectric eddies which print heads). restrict theflow through the inlet. The slower refill process is unrestricted, anddoes not result in eddies. Flexible In this method Significantly Notapplicable Canon flap recently disclosed reduces back- to most ink jetrestricts by Canon, the flow for edge- configurations inlet expandingactuator shooter thermal Increased (bubble) pushes on ink jet devicesfabrication a flexible flap that complexity restricts the inlet.Inelastic deformation of polymer flap results in creep over extended useInlet filter A filter is located Additional Restricts refill IJ04, IJ12,between the ink advantage of ink rate IJ24, IJ27, IJ29, inlet and thefiltration May result in IJ30 nozzle chamber. Ink filter may complex Thefilter has a be fabricated construction multitude of small with no holesor slots, additional restricting ink process steps flow. The filter alsoremoves particles which may block the nozzle. Small The ink inlet DesignRestricts refill IJ02, IJ37, inlet channel to the simplicity rate IJ44compared nozzle chamber May result in to nozzle has a substantially arelatively large smaller cross chip area section than that of Onlypartially the nozzle, effective resulting in easier ink egress out ofthe nozzle than out of the inlet. Inlet A secondary Increases RequiresIJ09 shutter actuator controls speed of the ink- separate refill theposition of a jet print head actuator and shutter, closing off operationdrive circuit the ink inlet when the main actuator is energized. Theinlet The method avoids Back-flow Requires IJ01, IJ03, is located theproblem of problem is careful design to IJ05, IJ06, IJ07, behind inletback-flow by eliminated minimize the IJ10, IJ11, IJ14, the ink-arranging the ink- negative IJ16, IJ22, IJ23, pushing pushing surface ofpressure behind IJ25, IJ28, IJ31, surface the actuator the paddle IJ32,IJ33, IJ34, between the inlet IJ35, IJ36, IJ39, and the nozzle. IJ40,IJ41 Part of The actuator and a Significant Small increase IJ07, IJ20,the wall of the ink reductions in in fabrication IJ26, IJ38 actuatorchamber are back-flow can be complexity moves to arranged so thatachieved shut off the motion of the Compact the inlet actuator closesoff designs possible the inlet. Nozzle In some Ink back-flow Nonerelated Silverbrook, actuator configurations of problem is to inkback-flow EP 0771 658 A2 does not ink jet, there is no eliminated onactuation and related result in expansion or patent ink back- movementof an applications flow actuator which Valve-jet may cause ink Tone-jetback-flow through the inlet.

NOZZLE CLEARING METHOD Description Advantages Disadvantages ExamplesNormal All of the nozzles No added May not be Most ink jet nozzle arefired complexity on sufficient to systems firing periodically, the printhead displace dried IJ01, IJ02, before the ink has ink IJ03, IJ04, IJ05,a chance to dry. IJ06, IJ07, IJ09, When not in use IJ10, IJ11, IJ12, thenozzles are IJ14, IJ16, IJ20, sealed (capped) IJ22, IJ23, IJ24, againstair. IJ25, IJ26, IJ27, The nozzle firing IJ28, IJ29, IJ30, is usuallyIJ31, IJ32, IJ33, performed during a IJ34, IJ36, IJ37, special clearingIJ38, IJ39, IJ40,, cycle, after first IJ41, IJ42, IJ43, moving the printIJ44,, IJ45 head to a cleaning station. Extra In systems which Can behighly Requires Silverbrook, power to heat the ink, but do effective ifthe higher drive EP 0771 658 A2 ink heater not boil it under heater isvoltage for and related normal situations, adjacent to the clearingpatent nozzle clearing can nozzle May require applications be achievedby larger drive over-powering the transistors heater and boiling ink atthe nozzle. Rapid The actuator is Does not Effectiveness May be usedsuccession fired in rapid require extra depends with: IJ01, IJ02, ofsuccession. In drive circuits on substantially IJ03, IJ04, IJ05,actuator some the print head upon the IJ06, IJ07, IJ09, pulsesconfigurations, this Can be readily configuration of IJ10, IJ11, IJ14,may cause heat controlled and the ink jet nozzle IJ16, IJ20, IJ22,build-up at the initiated by IJ23, IJ24, IJ25, nozzle which boilsdigital logic IJ27, IJ28, IJ29, the ink, clearing IJ30, IJ31, IJ32, thenozzle. In other IJ33, IJ34, IJ36, situations, it may IJ37, IJ38, IJ39,cause sufficient IJ40, IJ41, IJ42, vibrations to IJ43, IJ44, IJ45dislodge clogged nozzles. Extra Where an actuator A simple Not suitableMay be used power to is not normally solution where where there is awith: IJ03, IJ09, ink driven to the limit applicable hard limit to IJ16,IJ20, IJ23, pushing of its motion, actuator IJ24, IJ25, IJ27, actuatornozzle clearing movement IJ29, IJ30, IJ31, may be assisted by IJ32,IJ39, IJ40, providing an IJ41, IJ42, IJ43, enhanced drive IJ44, IJ45signal to the actuator. Acoustic An ultrasonic A high nozzle High IJ08,IJ13, resonance wave is applied to clearing implementation IJ15, IJ17,IJ18, the ink chamber. capability can be cost if system IJ19, IJ21 Thiswave is of an achieved does not already appropriate May be include anamplitude and implemented at acoustic actuator frequency to cause verylow cost in sufficient force at systems which the nozzle to clearalready include blockages. This is acoustic easiest to achieve actuatorsif the ultrasonic wave is at a resonant frequency of the ink cavity.Nozzle A microfabricated Can clear Accurate Silverbrook, clearing plateis pushed severely clogged mechanical EP 0771 658 A2 plate against thenozzles alignment is and related nozzles. The plate required patent hasa post for Moving parts applications every nozzle. A are required postmoves There is risk through each of damage to the nozzle, displacingnozzles dried ink. Accurate fabrication is required Ink The pressure ofthe May be Requires May be used pressure ink is temporarily effectivewhere pressure pump with all IJ series pulse increased so that othermethods or other pressure ink jets ink streams from cannot be usedactuator all of the nozzles. Expensive This may be used Wasteful of inconjunction ink with actuator energizing. Print A flexible ‘blade’Effective for Difficult to Many ink jet head is wiped across the planarprint head use if print head systems wiper print head surface. surfacessurface is non- The blade is Low cost planar or very usually fabricatedfragile from a flexible Requires polymer, e.g. mechanical parts rubberor synthetic Blade can elastomer. wear out in high volume print systemsSeparate A separate heater Can be Fabrication Can be used ink isprovided at the effective where complexity with many IJ boiling nozzlealthough other nozzle series ink jets heater the normal drop e- clearingmethods ection mechanism cannot be used does not require it. Can be Theheaters do not implemented at require individual no additional drivecircuits, as cost in some ink many nozzles can jet be clearedconfigurations simultaneously, and no imaging is required.

NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages ExamplesElectroformed A nozzle plate is Fabrication High Hewlett nickelseparately simplicity temperatures and Packard Thermal fabricated frompressures are Ink jet electroformed required to bond nickel, and bondednozzle plate to the print head Minimum chip. thickness constraintsDifferential thermal expansion Laser Individual nozzle No masks Eachhole Canon ablated or holes are ablated required must be Bubblejetdrilled by an intense UV Can be quite individually 1988 Sercel etpolymer laser in a nozzle fast formed al., SPIE, Vol. plate, which isSome control Special 998 Excimer typically a over nozzle equipment Beampolymer such as profile is required Applications, pp. polyimide orpossible Slow where 76-83 polysulphone Equipment there are many 1993required is thousands of Watanabe et al., relatively low nozzles perprint U.S. Pat. No. 5,208,604 cost head May produce thin burrs at exitholes Silicon A separate nozzle High accuracy Two part K. Bean,micromachined plate is is attainable construction IEEE micromachinedHigh cost Transactions on from single crystal Requires Electron silicon,and precision Devices, Vol. bonded to the print alignment ED-25, No. 10,head wafer. Nozzles may 1978, pp 1185-1195 be clogged by Xerox 1990adhesive Hawkins et al., U.S. Pat. No. 4,899,181 Glass Fine glass Noexpensive Very small 1970 Zoltan capillaries capillaries are equipmentnozzle sizes are U.S. Pat. No. 3,683,212 drawn from glass requireddifficult to form tubing. This Simple to Not suited for method has beenmake single mass production used for making nozzles individual nozzles,but is difficult to use for bulk manufacturing of print heads withthousands of nozzles. Monolithic, The nozzle plate is High accuracyRequires Silverbrook, surface deposited as a (<1 μm) sacrificial layerEP 0771 658 A2 micromachined layer using Monolithic under the nozzle andrelated using standard VLSI Low cost plate to form the patent VLSIdeposition Existing nozzle chamber applications lithographic techniques.processes can be Surface may IJ01, IJ02, processes Nozzles are etchedused be fragile to the IJ04, IJ11, IJ12, in the nozzle plate touch IJ17,IJ18, IJ20, using VLSI IJ22, IJ24, IJ27, lithography and IJ28, IJ29,IJ30, etching. IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40,IJ41, IJ42, IJ43, IJ44 Monolithic, The nozzle plate is High accuracyRequires long IJ03, IJ05, etched a buried etch stop (<1 μm) etch timesIJ06, IJ07, IJ08, through in the wafer. Monolithic Requires a IJ09,IJ10, IJ13, substrate Nozzle chambers Low cost support wafer IJ14, IJ15,IJ16, are etched in the No differential IJ19, IJ21, IJ23, front of thewafer, expansion IJ25, IJ26 and the wafer is thinned from the back side.Nozzles are then etched in the etch stop layer. No nozzle Variousmethods No nozzles to Difficult to Ricoh 1995 plate have been tried tobecome clogged control drop Sekiya et al U.S. Pat. No. eliminate theposition 5,412,413 nozzles entirely, to accurately 1993 prevent nozzleCrosstalk Hadimioglu et al clogging. These problems EUP 550,192 includethermal 1993 Elrod et bubble al EUP 572,220 mechanisms and acoustic lensmechanisms Trough Each drop ejector Reduced Drop firing IJ35 has atrough manufacturing direction is through which a complexity sensitiveto paddle moves. Monolithic wicking. There is no nozzle plate. Nozzleslit The elimination of No nozzles to Difficult to 1989 Saito et insteadof nozzle holes and become clogged control drop al U.S. Pat. No.individual replacement by a position 4,799,068 nozzles slit encompassingaccurately many actuator Crosstalk positions reduces problems nozzleclogging, but increases crosstalk due to ink surface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages ExamplesEdge Ink flow is along Simple Nozzles Canon (‘edge the surface of theconstruction limited to edge Bubblejet 1979 shooter’) chip, and inkdrops No silicon High Endo et al GB are ejected from etching requiredresolution is patent 2,007,162 the chip edge. Good heat difficult Xeroxheater- sinking via Fast color in-pit 1990 substrate printing requiresHawkins et al Mechanically one print head U.S. Pat. No. 4,899,181 strongper color Tone-jet Ease of chip handing Surface Ink flow is along Nobulk Maximum ink Hewlett- (‘roof the surface of the silicon etching flowis severely Packard TIJ shooter’) chip, and ink drops requiredrestricted 1982 Vaught et are ejected from Silicon can al U.S. Pat. No.the chip surface, make an 4,490,728 normal to the effective heat IJ02,IJ11, plane of the chip. sink IJ12, IJ20, IJ22 Mechanical strengthThrough Ink flow is through High ink flow Requires bulk Silverbrook,chip, the chip, and ink Suitable for silicon etching EP 0771 658 A2forward drops are ejected pagewidth print and related (‘up from thefront heads patent shooter’) surface of the chip. High nozzleapplications packing density IJ04, IJ17, therefore low IJ18, IJ24,IJ27-IJ45 manufacturing cost Through Ink flow is through High ink flowRequires IJ01, IJ03, chip, the chip, and ink Suitable for wafer thinningIJ05, IJ06, IJ07, reverse drops are ejected pagewidth print RequiresIJ08, IJ09, IJ10, (‘down from the rear heads special handling IJ13,IJ14, IJ15, shooter’) surface of the chip. High nozzle during IJ16,IJ19, IJ21, packing density manufacture IJ23, IJ25, IJ26 therefore lowmanufacturing cost Through Ink flow is through Suitable for PagewidthEpson Stylus actuator the actuator, which piezoelectric print headsTektronix hot is not fabricated as print heads require several melt partof the same thousand piezoelectric ink substrate as the connections tojets drive transistors. drive circuits Cannot be manufactured instandard CMOS fabs Complex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Waterbased ink Environmentally Slow drying Most existing dye which typicallyfriendly Corrosive ink jets contains: water, No odor Bleeds on All IJseries dye, surfactant, paper ink jets humectant, and May Silverbrook,biocide. strikethrough EP 0771 658 A2 Modern ink dyes Cockles paper andrelated have high water- patent fastness, light applications fastnessAqueous, Water based ink Environmentally Slow drying IJ02, IJ04, pigmentwhich typically friendly Corrosive IJ21, IJ26, IJ27, contains: water, Noodor Pigment may IJ30 pigment, Reduced bleed clog nozzles Silverbrook,surfactant, Reduced Pigment may EP 0771 658 A2 humectant, and wickingclog actuator and related biocide. Reduced mechanisms patent Pigmentshave an strikethrough Cockles paper applications advantage inPiezoelectric reduced bleed, ink-jets wicking and Thermal inkstrikethrough. jets (with significant restrictions) Methyl MEK is ahighly Very fast Odorous All IJ series Ethyl volatile solvent dryingFlammable ink jets Ketone used for industrial Prints on (MEK) printingon various difficult surfaces substrates such such as aluminum as metalsand cans. plastics Alcohol Alcohol based inks Fast drying Slight odorAll IJ series (ethanol, can be used where Operates at Flammable ink jets2-butanol, the printer must sub-freezing and operate at temperaturesothers) temperatures Reduced below the freezing paper cockle point ofwater. An Low cost example of this is in-camera consumer photographicprinting. Phase The ink is solid at No drying High viscosity Tektronixhot change room temperature, time-ink Printed ink melt (hot melt) and ismelted in instantly freezes typically has a piezoelectric ink the printhead on the print ‘waxy’ feel jets before jetting. Hot medium Printedpages 1989 Nowak melt inks are Almost any may ‘block’ U.S. Pat. No.4,820,346 usually wax based, print medium Ink All IJ series with amelting can be used temperature may ink jets point around 80° C. Nopaper be above the After jetting cockle occurs curie point of the inkfreezes No wicking permanent almost instantly occurs magnets uponcontacting No bleed Ink heaters the print medium occurs consume power ora transfer roller. No Long warm- strikethrough up time occurs Oil Oilbased inks are High High All IJ series extensively used in solubilityviscosity: this is ink jets offset printing. medium for a significantThey have some dyes limitation for use advantages in Does not in inkjets, which improved cockle paper usually require a characteristics onDoes not wick low viscosity. paper (especially through paper Some shortno wicking or chain and multi- cockle). Oil branched oils soluble diesand have a pigments are sufficiently low required. viscosity. Slowdrying Microemulsion A microemulsion Stops ink Viscosity All IJ seriesis a stable, self bleed higher than ink jets forming emulsion High dyewater of oil, water, and solubility Cost is surfactant. The Water, oil,slightly higher characteristic drop and amphiphilic than water basedsize is less than soluble dies can ink 100 nm, and is be used Highdetermined by the Can stabilize surfactant preferred curvature pigmentconcentration of the surfactant. suspensions required (around 5%)

1. A printhead integrated circuit that comprises a substrate; anexternal surface having a number of ink ejection ports operativelydirected at a printing medium, the surface and the substrate defining aplurality of ink chambers in fluid communication with respective inkejection ports, said surface comprising: a plurality of petal formationsradially positioned about each ink ejection port; a plurality ofactuators, each located behind a petal formation distal from said port;and a plurality of heater structures each connected to an actuator, sothat heating of the structures via an electrical current producesdifferential thermal expansion in said actuators which urges theformations into the ink chambers.
 2. The printhead integrated circuit ofclaim 1, wherein the actuators are manufactured from apolytetrafluoroethylene (PTFE) material and have an internal serpentinecopper core which forms the heater structures.
 3. The printheadintegrated circuit of claim 1, which includes a number of central armsradially positioned about the port between the petal formations toprovide structural support for the formations.
 4. The printheadintegrated circuit of claim 1, which defines a rim about the ejectionport.
 5. The printhead integrated circuit of claim 1, wherein theactuators are manufactured from a material having a coefficient ofthermal expansion sufficiently high so that the actuators can performwork when they expand.
 6. The printhead integrated circuit of claim 1,which includes an integrated layer of CMOS circuitry which drives theheater structures.
 7. The printhead integrated circuit of claim 6, whichdefines a number of vias through which the CMOS drive circuitry isconnected to the heater structures.